By Jeff Andresen
Scattered showers and thunderstorms brought much-needed moisture to extreme northwestern, central and eastern sections of Michigan, but rainfall totals in other areas were negligible. Symptoms of plant water stress were evident in many spots, especially across the southwestern Lower Peninsula where rainfall deficits since May 1 are now approaching 6 inches in some cases (8 to 9 inches is the climatological norm). The moisture stress was exacerbated by unusually high temperatures during the first week of July, with 100-plus degrees Fahrenheit maxima reported in southern sections.
While forecast guidance does suggest some relief to heat and dryness during the next week, medium range guidance continues to suggest a general continuation of drier than normal weather into the second half of July. The magnitude of heat and dryness across southern Michigan and much of the central and eastern Corn Belt region to our south is very unusual, with similar conditions not observed since the great drought of 1988.
Latest medium range forecast guidance suggests that the persistent upper air ridge responsible for the drought will shift from western sections of North America early next week back to the Midwest by late next week. Unfortunately, this pattern change will likely lead to a return of much above normal temperatures at some point during the next one to two weeks.
The latest NOAA Climate Prediction Center 6-to-10 day and 8-to-14 day outlooks (for July 10-14 and July 12-18) both call precipitation totals to continue to remain at below normal levels state- and region-wide.
Mean temperatures during the 6-to-10 day timeframe are forecast to range from below normal levels across extreme eastern sections of the state to above normal levels in the west, warming to near to above normal levels statewide during the 8-to-14 day period.
Dr. Andresen's work is funded in part by MSU's AgBioResearch. He writes from Michigan State University Extension, Department of Geography